[MPlayer-users] lavc vs. xvid (and improving lavc quality)

[Vladimir Mosgalin]

On Tue, 1 Jun 2004, D Richard Felker III wrote:

DRFI>> *looks puzzled* Which gamma correction?
DRFI>> 
DRFI>> I mean that my monitor's brightness is tweaked to the right level, and
DRFI>
DRFI>No, it's tweaked to the wrong level. That's the problem. Intensity
DRFI>in movies is NOT linear; it's designed for the nonlinearity in
DRFI>CRTs. BTW this is a GOOD thing, since you need more precision at
DRFI>lower intensities or you'll see ugly bands/blocks.

If the 2.5 gamma isn't right, then what should I tweak to? To stupid
sRGB? No thanks.

DRFI>> gamma is set to 1.01, 1.05 & 1.04 for rgb to get the correct 2.5 gamma.
DRFI>> I use no gamma correction in mplayer, but I use -vf x11 to pick those
DRFI>> values up.
DRFI>I hope you don't normally use -vf x11, since it will tear!!

I do ;) I don't mind tearing, really.

DRFI>> OK, I'm gonna try xvid and tell if I see the same problems. Maybe really
DRFI>> it's time to say goodbye to lavc. It may be good at middle & low
DRFI>> bitrates, but when trying to encode dvds to get vhq rips, its behaviour
DRFI>> isn't good.
DRFI>
DRFI>This is nonsense. lavc gives much better psnr and much higher visual
DRFI>quality (no artifacts whatsoever!) compared to xvid and divx, which
DRFI>are about the same (after all they're from the same codebase).

Well, first check shown that vqmin=2:vqmax=2:vbitrate=10000 instead of
vbitrate really generates better picture.

DRFI>I've seen bad blocking artifacts on DVDs, but noise is much more
DRFI>common. The noise actually serves to mask out the blocking artifacts,
DRFI>same as if you use -vf noise, but it wastes a LOT of space. Better to
DRFI>denoise and add noise back during playback if you really insist. But
DRFI>seriously... With a GOOD monitor, CORRECT brightness/gamma settings,
DRFI>and proper encoding flags, you don't need anny noise/postproc. There
DRFI>just aren't any artifacts.

IMHO a very small noise always makes the picture better.

-- 

Vladimir